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From c449946b9d06571b447fce3fc0dcad89e8df05b5 Mon Sep 17 00:00:00 2001
From: Bart Van Assche <bvanassche@acm.org>
Date: Wed, 15 May 2019 14:09:25 +0200
Subject: [PATCH 1/5] CHANGES: libsnmp: Scan MIB directories in alphabetical
order
This guarantees that e.g. mibs/RFC1213-MIB.txt is read before mibs/SNMPv2-MIB.txt.
The order in which these MIBs is read matters because both define sysLocation but
with different attributes.
CVE: CVE-2020-15861
Upstream-Status: Backport [https://github.com/net-snmp/net-snmp/commit/2b3e300ade4add03b889e61d610b0db77d300fc3]
Signed-off-by: Ovidiu Panait <ovidiu.panait@windriver.com>
---
snmplib/parse.c | 113 +++++++++++++++++++++++++++++++++++-------------
1 file changed, 82 insertions(+), 31 deletions(-)
diff --git a/snmplib/parse.c b/snmplib/parse.c
index 7678b35..51d119b 100644
--- a/snmplib/parse.c
+++ b/snmplib/parse.c
@@ -4894,6 +4894,79 @@ add_mibfile(const char* tmpstr, const char* d_name, FILE *ip )
}
}
+static int elemcmp(const void *a, const void *b)
+{
+ const char *const *s1 = a, *const *s2 = b;
+
+ return strcmp(*s1, *s2);
+}
+
+/*
+ * Scan a directory and return all filenames found as an array of pointers to
+ * directory entries (@result).
+ */
+static int scan_directory(char ***result, const char *dirname)
+{
+ DIR *dir, *dir2;
+ struct dirent *file;
+ char **filenames = NULL;
+ int fname_len, i, filename_count = 0, array_size = 0;
+ char *tmpstr;
+
+ *result = NULL;
+
+ dir = opendir(dirname);
+ if (!dir)
+ return -1;
+
+ while ((file = readdir(dir))) {
+ /*
+ * Only parse file names that don't begin with a '.'
+ * Also skip files ending in '~', or starting/ending
+ * with '#' which are typically editor backup files.
+ */
+ fname_len = strlen(file->d_name);
+ if (fname_len > 0 && file->d_name[0] != '.'
+ && file->d_name[0] != '#'
+ && file->d_name[fname_len-1] != '#'
+ && file->d_name[fname_len-1] != '~') {
+ if (asprintf(&tmpstr, "%s/%s", dirname, file->d_name) < 0)
+ continue;
+ dir2 = opendir(tmpstr);
+ if (dir2) {
+ /* file is a directory, don't read it */
+ closedir(dir2);
+ } else {
+ if (filename_count >= array_size) {
+ char **new_filenames;
+
+ array_size = (array_size + 16) * 2;
+ new_filenames = realloc(filenames,
+ array_size * sizeof(filenames[0]));
+ if (!new_filenames) {
+ free(tmpstr);
+ for (i = 0; i < filename_count; i++)
+ free(filenames[i]);
+ free(filenames);
+ closedir(dir);
+ return -1;
+ }
+ filenames = new_filenames;
+ }
+ filenames[filename_count++] = tmpstr;
+ tmpstr = NULL;
+ }
+ free(tmpstr);
+ }
+ }
+ closedir(dir);
+
+ qsort(filenames, filename_count, sizeof(filenames[0]), elemcmp);
+ *result = filenames;
+
+ return filename_count;
+}
+
/* For Win32 platforms, the directory does not maintain a last modification
* date that we can compare with the modification date of the .index file.
* Therefore there is no way to know whether any .index file is valid.
@@ -4904,12 +4977,11 @@ int
add_mibdir(const char *dirname)
{
FILE *ip;
- DIR *dir, *dir2;
const char *oldFile = File;
- struct dirent *file;
+ char **filenames;
char tmpstr[300];
int count = 0;
- int fname_len = 0;
+ int filename_count, i;
#if !(defined(WIN32) || defined(cygwin))
char *token;
char space;
@@ -4957,36 +5029,15 @@ add_mibdir(const char *dirname)
DEBUGMSGTL(("parse-mibs", "No index\n"));
#endif
- if ((dir = opendir(dirname))) {
- ip = netsnmp_mibindex_new( dirname );
- while ((file = readdir(dir))) {
- /*
- * Only parse file names that don't begin with a '.'
- * Also skip files ending in '~', or starting/ending
- * with '#' which are typically editor backup files.
- */
- if (file->d_name != NULL) {
- fname_len = strlen( file->d_name );
- if (fname_len > 0 && file->d_name[0] != '.'
- && file->d_name[0] != '#'
- && file->d_name[fname_len-1] != '#'
- && file->d_name[fname_len-1] != '~') {
- snprintf(tmpstr, sizeof(tmpstr), "%s/%s", dirname, file->d_name);
- tmpstr[ sizeof(tmpstr)-1 ] = 0;
- if ((dir2 = opendir(tmpstr))) {
- /*
- * file is a directory, don't read it
- */
- closedir(dir2);
- } else {
- if ( !add_mibfile( tmpstr, file->d_name, ip ))
- count++;
- }
- }
- }
+ filename_count = scan_directory(&filenames, dirname);
+
+ if (filename_count >= 0) {
+ ip = netsnmp_mibindex_new(dirname);
+ for (i = 0; i < filename_count; i++) {
+ if (add_mibfile(filenames[i], strrchr(filenames[i], '/'), ip) == 0)
+ count++;
}
File = oldFile;
- closedir(dir);
if (ip)
fclose(ip);
return (count);
--
2.17.1
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